INTRODUCTION TO OOP

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INTRODUCTION TO OOP

• Objective
• Know the difference between functional
  programming
• and OOP
• Know basic terminology in OOP
• Know the importance of OOP
• Know four design principles of OOP
• Know OOP programming languages

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STRUCTURED vs. OO PROGRAMMING
STRUCTURED PROGRAMMING
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Structured Programming

• Using function
• Function program is divided into modules
• Every module has its own data and function which
  can be called by other modules.

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OBJECT ORIENTED PROGRAMMING
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OBJECT ORIENTED PROGRAMMING

• Objects have both data and methods
• Objects of the same class have the same data
  elements and methods
• Objects send and receive messages to invoke
  actions
• Key idea in object-oriented
•  
• The real world can be accurately described as a
  collection of objects that interact.

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• Basic terminology
• object
• - usually a person, place or thing (a noun)
• method
• - an action performed by an object (a verb)
• attribute
• - description of objects in a class
• class
• - a category of similar objects (such as
  automobiles)
• - does not hold any values of the objects
  attributes

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Example for attributes and methods

• Attributes
• manufacturers name
• model name
• year made
• color
• number of doors
• size of engine
• etc.

• Methods
• Define data items (specify manufacturers name,
  model, year, etc.)
• Change a data item (color, engine, etc.)
• Display data items
• Calculate cost
• etc.

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Why OOP?

• Save development time (and cost) by reusing code
• once an object class is created it can be used in
  other applications
• Easier debugging
• classes can be tested independently
• reused objects have already been tested

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Design Principles of OOP

• Four main design principles of Object-Oriented
  Programming(OOP)
• Encapsulation
• Abstraction
• Polymorphism
• Inheritance

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Encapsulation

• Also known as data hiding
• Only objects methods can modify information in
  the object.
• Analogy
• ATM machine can only update accounts of one
  person or object only.

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Abstraction

• Focus only on the important facts about the
  problem at hand
• to design, produce, and describe so that it can
  be easily used without knowing the details of how
  it works.
• Analogy
• When you drive a car, you dont have to know how
  the gasoline and air are mixed and ignited.
• Instead you only have to know how to use the
  controls.
• Draw map

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Polymorphism

• the same word or phrase can mean different things
  in different contexts
• Analogy
• In English, bank can mean side of a river or a
  place to put money
• move -

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Function Overloading

• The operation of one function depends on the
  argument passed to it.
• Example Fly(), Fly(low), Fly(150)

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Inheritance

• Inheritancea way of organizing classes
• Term comes from inheritance of traits like eye
  color, hair color, and so on.
• Classes with properties in common can be grouped
  so that their common properties are only defined
  once.
• Superclass inherit its attributes methods to
  the subclass(es).
• Subclass can inherit all its superclass
  attributes methods besides having its own
  unique attributes methods.

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An Inheritance Hierarchy
Superclass
Vehicle
Subclasses
Automobile
Motorcycle
Bus
Sedan
Sports Car
School Bus
Luxury Bus
What properties does each vehicle inherit from
the types of vehicles above it in the diagram?
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Object-Oriented Programming Languages

•         Pure OO Languages
• Smalltalk, Eiffel, Actor, Java
•  
•         Hybrid OO Languages
• C, Objective-C, Object-Pascal

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Review Introduction to Object Orientation

• What are the four basic principles of object
  orientation? Provide a brief description of
  each.
• What is an Object and what is a Class? What is
  the difference between them?
• What is an Attribute?
• What is an Operation?
• What is inheritance?
• What is polymorphism?
• Describe the strengths of object orientation.

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Review Introduction to Object Orientation

• State 2 differences between functional
  programming and OOP.
• What are the four basic principles of object
  orientation? Provide a brief description of
  each.
• What is an Object and what is a Class? What is
  the difference between them?
• What is an Attribute?
• What is an Operation?
• Describe the strengths of object orientation.